Isolation and immunochemical characterization of the alcohol-extractable proteins (kafirins) of Sorghum bicolor (L.) Moench

Abstract

The differential extractabilities of kafirins were exploited in purifying α-, β- and γ- kafirins. Polyclonal antibodies were raised against them. Immunoblotting showed no cross reactivity between the three kafirins. Nitrogen analysis, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting and enzyme linked immunosorbent assay (ELISA) were used to demonstrate the qualitative and quantitative differences between kafirins and cross-linked kafirins. ELISA indicated that increased extractability of β- and γ-kafirins was responsible for the increase in the total kafirin extracted when a reducing agent was added to aqueous t-butanol. All three kafirin antibodies reacted with specific prolamins from other tropical millets and cereals suggesting homologies amongst the prolamins contained within them.